Welcome to the site ....
You wouldn't be the first to grow up and move from a ZR to a ZS ....
Plenty of engine options all with a degree of tuning potential, the derv in my view giving the best improvement per pound over standard if you're into modifying. The 180 has by far the best soundtrack and very good performance in standard fom but costly to eek out more than 200bhp.
As for practicality, don't feel tied to a hatch. It's a very good and practical car, but the saloon has a very different look, and a mahoooosive boot.
As for someone swapping into yours, your ZR looks awesome, whether it'd tempt someone from their ZS - not sure.